text: /* ----------------------------------------------------------------------
  * Copyright (C) 2010 ARM Limited. All rights reserved.
  *
  * $Date:        29. November 2010
  * $Revision:    V1.0.3
  *
  * Project:      CMSIS DSP Library
  *
  * Title:        math_helper.c
  *
  * Description:  Definition of all helper functions required.
  *
  * Target Processor: Cortex-M4/Cortex-M3
  *
  * Version 1.0.3 2010/11/29
  *    Re-organized the CMSIS folders and updated documentation.
  *
  * Version 1.0.2 2010/11/11
  *    Documentation updated.
  *
  * Version 1.0.1 2010/10/05
  *    Production release and review comments incorporated.
  *
  * Version 1.0.0 2010/09/20
  *    Production release and review comments incorporated.
  *
  * Version 0.0.7  2010/06/10
  *    Misra-C changes done
  * -------------------------------------------------------------------- */
  
  /* ----------------------------------------------------------------------
  *       Include standard header files
  * -------------------------------------------------------------------- */
  #include<math.h>
  
  /* ----------------------------------------------------------------------
  *       Include project header files
  * -------------------------------------------------------------------- */
  #include "math_helper.h"
  
  /**
   * @brief  Caluclation of SNR
   * @param  float*   Pointer to the reference buffer
   * @param  float*   Pointer to the test buffer
   * @param  uint32_t     total number of samples
   * @return float    SNR
   * The function Caluclates signal to noise ratio for the reference output
   * and test output
   */
  
  float arm_snr_f32(float *pRef, float *pTest, uint32_t buffSize)
  {
    float EnergySignal = 0.0, EnergyError = 0.0;
    uint32_t i;
    float SNR;
    int temp;
    int *test;
  
    for (i = 0; i < buffSize; i++)
      {
        /* Checking for a NAN value in pRef array */
        test =   (int *)(&pRef[i]);
        temp =  *test;
  
        if (temp == 0x7FC00000)
        {
              return(0);
        }
  
        /* Checking for a NAN value in pTest array */
        test =   (int *)(&pTest[i]);
        temp =  *test;
  
        if (temp == 0x7FC00000)
        {
              return(0);
        }
        EnergySignal += pRef[i] * pRef[i];
        EnergyError += (pRef[i] - pTest[i]) * (pRef[i] - pTest[i]);
      }
  
      /* Checking for a NAN value in EnergyError */
      test =   (int *)(&EnergyError);
      temp =  *test;
  
      if (temp == 0x7FC00000)
      {
          return(0);
      }
  
  
    SNR = 10 * log10f (EnergySignal / EnergyError);
  
  	return (SNR);
  
  }
  
  
  
  double arm_snr_f64(double *pRef, double *pTest, uint32_t buffSize)
  {
    double EnergySignal = 0.0, EnergyError = 0.0;
    uint32_t i;
    double SNR;
    int temp;
    int *test;
  
    for (i = 0; i < buffSize; i++)
      {
        /* Checking for a NAN value in pRef array */
        test =   (int *)(&pRef[i]);
        temp =  *test;
  
        if (temp == 0x7FC00000)
        {
              return(0);
        }
  
        /* Checking for a NAN value in pTest array */
        test =   (int *)(&pTest[i]);
        temp =  *test;
  
        if (temp == 0x7FC00000)
        {
              return(0);
        }
        EnergySignal += pRef[i] * pRef[i];
        EnergyError += (pRef[i] - pTest[i]) * (pRef[i] - pTest[i]);
      }
  
      /* Checking for a NAN value in EnergyError */
      test =   (int *)(&EnergyError);
      temp =  *test;
  
      if (temp == 0x7FC00000)
      {
          return(0);
      }
  
  
    SNR = 10 * log10 (EnergySignal / EnergyError);
  
    return (SNR);
  
  }
  
  /**
   * @brief  Provide guard bits for Input buffer
   * @param  q15_t*       Pointer to input buffer
   * @param  uint32_t     blockSize
   * @param  uint32_t     guard_bits
   * @return none
   * The function Provides the guard bits for the buffer
   * to avoid overflow
   */
  
  void arm_provide_guard_bits_q15 (q15_t * input_buf, uint32_t blockSize,
                              uint32_t guard_bits)
  {
    uint32_t i;
  
    for (i = 0; i < blockSize; i++)
      {
        input_buf[i] = input_buf[i] >> guard_bits;
      }
  }
  
  /**
   * @brief  Converts float to fixed in q12.20 format
   * @param  uint32_t     number of samples in the buffer
   * @return none
   * The function converts floating point values to fixed point(q12.20) values
   */
  
  void arm_float_to_q12_20(float *pIn, q31_t * pOut, uint32_t numSamples)
  {
    uint32_t i;
  
    for (i = 0; i < numSamples; i++)
      {
        /* 1048576.0f corresponds to pow(2, 20) */
        pOut[i] = (q31_t) (pIn[i] * 1048576.0f);
  
        pOut[i] += pIn[i] > 0 ? 0.5 : -0.5;
  
        if (pIn[i] == (float) 1.0)
          {
            pOut[i] = 0x000FFFFF;
          }
      }
  }
  
  /**
   * @brief  Compare MATLAB Reference Output and ARM Test output
   * @param  q15_t*   Pointer to Ref buffer
   * @param  q15_t*   Pointer to Test buffer
   * @param  uint32_t     number of samples in the buffer
   * @return none
   */
  
  uint32_t arm_compare_fixed_q15(q15_t *pIn, q15_t * pOut, uint32_t numSamples)
  {
    uint32_t i;
    int32_t diff, diffCrnt = 0;
    uint32_t maxDiff = 0;
  
    for (i = 0; i < numSamples; i++)
    {
      diff = pIn[i] - pOut[i];
      diffCrnt = (diff > 0) ? diff : -diff;
  
      if (diffCrnt > maxDiff)
      {
          maxDiff = diffCrnt;
      }
    }
  
    return(maxDiff);
  }
  
  /**
   * @brief  Compare MATLAB Reference Output and ARM Test output
   * @param  q31_t*   Pointer to Ref buffer
   * @param  q31_t*   Pointer to Test buffer
   * @param  uint32_t     number of samples in the buffer
   * @return none
   */
  
  uint32_t arm_compare_fixed_q31(q31_t *pIn, q31_t * pOut, uint32_t numSamples)
  {
    uint32_t i;
    int32_t diff, diffCrnt = 0;
    uint32_t maxDiff = 0;
  
    for (i = 0; i < numSamples; i++)
    {
      diff = pIn[i] - pOut[i];
      diffCrnt = (diff > 0) ? diff : -diff;
  
      if (diffCrnt > maxDiff)
      {
          maxDiff = diffCrnt;
      }
    }
  
    return(maxDiff);
  }
  
  /**
   * @brief  Provide guard bits for Input buffer
   * @param  q31_t*   Pointer to input buffer
   * @param  uint32_t     blockSize
   * @param  uint32_t     guard_bits
   * @return none
   * The function Provides the guard bits for the buffer
   * to avoid overflow
   */
  
  void arm_provide_guard_bits_q31 (q31_t * input_buf,
                                   uint32_t blockSize,
                                   uint32_t guard_bits)
  {
    uint32_t i;
  
    for (i = 0; i < blockSize; i++)
      {
        input_buf[i] = input_buf[i] >> guard_bits;
      }
  }
  
  /**
   * @brief  Provide guard bits for Input buffer
   * @param  q31_t*   Pointer to input buffer
   * @param  uint32_t     blockSize
   * @param  uint32_t     guard_bits
   * @return none
   * The function Provides the guard bits for the buffer
   * to avoid overflow
   */
  
  void arm_provide_guard_bits_q7 (q7_t * input_buf,
                                  uint32_t blockSize,
                                  uint32_t guard_bits)
  {
    uint32_t i;
  
    for (i = 0; i < blockSize; i++)
      {
        input_buf[i] = input_buf[i] >> guard_bits;
      }
  }
  
  
  
  /**
   * @brief  Caluclates number of guard bits
   * @param  uint32_t     number of additions
   * @return none
   * The function Caluclates the number of guard bits
   * depending on the numtaps
   */
  
  uint32_t arm_calc_guard_bits (uint32_t num_adds)
  {
    uint32_t i = 1, j = 0;
  
    if (num_adds == 1)
      {
        return (0);
      }
  
    while (i < num_adds)
      {
        i = i * 2;
        j++;
      }
  
    return (j);
  }
  
  /**
   * @brief  Converts Q15 to floating-point
   * @param  uint32_t     number of samples in the buffer
   * @return none
   */
  
  void arm_apply_guard_bits (float32_t * pIn,
                             uint32_t numSamples,
                             uint32_t guard_bits)
  {
    uint32_t i;
  
    for (i = 0; i < numSamples; i++)
      {
        pIn[i] = pIn[i] * arm_calc_2pow(guard_bits);
      }
  }
  
  /**
   * @brief  Calculates pow(2, numShifts)
   * @param  uint32_t     number of shifts
   * @return pow(2, numShifts)
   */
  uint32_t arm_calc_2pow(uint32_t numShifts)
  {
  
    uint32_t i, val = 1;
  
    for (i = 0; i < numShifts; i++)
      {
        val = val * 2;
      }
  
    return(val);
  }
  
  
  
  /**
   * @brief  Converts float to fixed q14
   * @param  uint32_t     number of samples in the buffer
   * @return none
   * The function converts floating point values to fixed point values
   */
  
  void arm_float_to_q14 (float *pIn, q15_t * pOut,
                         uint32_t numSamples)
  {
    uint32_t i;
  
    for (i = 0; i < numSamples; i++)
      {
        /* 16384.0f corresponds to pow(2, 14) */
        pOut[i] = (q15_t) (pIn[i] * 16384.0f);
  
        pOut[i] += pIn[i] > 0 ? 0.5 : -0.5;
  
        if (pIn[i] == (float) 2.0)
          {
            pOut[i] = 0x7FFF;
          }
  
      }
  
  }
  
  
  /**
   * @brief  Converts float to fixed q30 format
   * @param  uint32_t     number of samples in the buffer
   * @return none
   * The function converts floating point values to fixed point values
   */
  
  void arm_float_to_q30 (float *pIn, q31_t * pOut,
                         uint32_t numSamples)
  {
    uint32_t i;
  
    for (i = 0; i < numSamples; i++)
      {
        /* 1073741824.0f corresponds to pow(2, 30) */
        pOut[i] = (q31_t) (pIn[i] * 1073741824.0f);
  
        pOut[i] += pIn[i] > 0 ? 0.5 : -0.5;
  
        if (pIn[i] == (float) 2.0)
          {
            pOut[i] = 0x7FFFFFFF;
          }
      }
  }
  
  /**
   * @brief  Converts float to fixed q30 format
   * @param  uint32_t     number of samples in the buffer
   * @return none
   * The function converts floating point values to fixed point values
   */
  
  void arm_float_to_q29 (float *pIn, q31_t * pOut,
                         uint32_t numSamples)
  {
    uint32_t i;
  
    for (i = 0; i < numSamples; i++)
      {
        /* 1073741824.0f corresponds to pow(2, 30) */
        pOut[i] = (q31_t) (pIn[i] * 536870912.0f);
  
        pOut[i] += pIn[i] > 0 ? 0.5 : -0.5;
  
        if (pIn[i] == (float) 4.0)
          {
            pOut[i] = 0x7FFFFFFF;
          }
      }
  }
  
  
  /**
   * @brief  Converts float to fixed q28 format
   * @param  uint32_t     number of samples in the buffer
   * @return none
   * The function converts floating point values to fixed point values
   */
  
  void arm_float_to_q28 (float *pIn, q31_t * pOut,
                         uint32_t numSamples)
  {
    uint32_t i;
  
    for (i = 0; i < numSamples; i++)
      {
      /* 268435456.0f corresponds to pow(2, 28) */
        pOut[i] = (q31_t) (pIn[i] * 268435456.0f);
  
        pOut[i] += pIn[i] > 0 ? 0.5 : -0.5;
  
        if (pIn[i] == (float) 8.0)
          {
            pOut[i] = 0x7FFFFFFF;
          }
      }
  }
  
  /**
   * @brief  Clip the float values to +/- 1
   * @param  pIn      input buffer
   * @param  numSamples   number of samples in the buffer
   * @return none
   * The function converts floating point values to fixed point values
   */
  
  void arm_clip_f32 (float *pIn, uint32_t numSamples)
  {
    uint32_t i;
  
    for (i = 0; i < numSamples; i++)
      {
        if (pIn[i] > 1.0f)
        {
          pIn[i] = 1.0;
        }
        else if ( pIn[i] < -1.0f)
        {
          pIn[i] = -1.0;
        }
  
      }
  }
  